The present invention is directed, in general, to wireless communication networks and, more specifically, to a system for providing reliable delivery of medium access control (MAC) messages over the air interface of a wireless communication network.
Reliable predictions indicate that there will be over 300 million cellular telephone customers by the year 2000. Within the United States, cellular service is offered not only by dedicated cellular service providers, but also by the regional Bell companies, such as U.S. West, Bell Atlantic and Southwestern Bell, and the national long distance companies, such as ATandT and Sprint. The enhanced competition has driven the price of cellular service down to the point where it is affordable to a large segment of the population. As a result, wireless subscribers use a wide variety of wireless devices, including cellular phones, personal communication services (PCS) devices, and wireless modem-equipped personal computer (PCs), among others.
To maximize usage of the available bandwidth, a number of multiple access technologies have been implemented to allow more than one subscriber to communicate simultaneously in a wireless system. These multiple access technologies include time division multiple access (TDMA), frequency division multiple access (FDMA), and code division multiple access (CDMA). These technologies assign each system subscriber to a specific traffic channel that transmits and receives subscriber voice/data signals via a selected time slot, a selected frequency, a selected unique code, or a combination thereof.
Generally, a multiple access wireless system uses dedicated control channels to establish, to maintain, and to break down a connection between a subscriber""s mobile device (also called xe2x80x9cmobile unitxe2x80x9d or xe2x80x9cmobile stationxe2x80x9d) and the wireless system. The control channel signals transmitted between the base transceiver stations of the wireless system and the mobile units are generally referred to as medium access control (MAC) messages. The MAC layers of the base transceiver stations and the mobile units are the lower half of the data link layer that defines topology dependent access control protocols in a communication network. The MAC layer specifies the message frame formats as well as the conditions for accessing the traffic channels of the wireless network.
MAC messages are transmitted in a forward control channel from a base transceiver station to one or more mobile units and in a reverse control channel from the mobile station to the base transceiver station. At the start of a wireless telephone call or data transmission, the MAC messages establish a connection and assign the subscriber to a selected traffic channel. Once the connection is established, the subscriber and the base transceiver station exchange voice and/or data signals via the selected traffic channel. MAC messages are used to maintain the connection and to handle any hand-offs that are performed between base transceiver stations.
The performance and reliability of a wireless network is at least partially determined by the reliability with which MAC messages are exchanged between mobile units and base transceiver stations in the wireless network. If a MAC,message is lost in transmission or received out-of-sequence due to the loss of another MAC message, the wireless network typically must re-transmit at least one, and usually several, of the MAC messages in order to compensate for the one or more lost MAC messages.
There is therefore a need in the art for wireless networks that provide more reliable communications between mobile units and base transceiver stations in the wireless network. In particular, there is a need in the art for wireless networks that exchange MAC messages in a more reliable manner.
To address the above-discussed deficiencies of the prior art, it is a primary object of the present invention to provide, for use in a wireless communications device, a medium access control (MAC) message acknowledgment system for acknowledging MAC messages transmitted in an RF control channel between the wireless communications device and a remote communications unit. In one embodiment of the present invention, the MAC message acknowledgment system comprises a control processor capable of receiving an outbound MAC message unit from a MAC layer device in the wireless communications device and attaching a header to the outbound MAC message unit to thereby form an outbound MAC message suitable for transmission to the remote communications unit, the header comprising logic bits identifying the outbound MAC message unit to the remote communications device to thereby enable the remote communications unit to acknowledge receipt of the outbound MAC message.
In another embodiment of the present invention, the MAC message acknowledgment system further comprises a timer coupled to and controllable by the control processor, wherein the timer stores a delay period the MAC message acknowledgment system will wait before re-transmitting the outbound MAC message.
In still another embodiment of the present invention, the MAC message acknowledgment system further comprises a memory coupled to and controllable by the control processor, wherein the control processor stores the outbound MAC message in the memory if a receipt of a previously transmitted MAC message has not been acknowledged by the remote communications unit.
In yet another embodiment of the present invention, the wireless communications device is a mobile device.
In a further embodiment of the present invention, the wireless communications device is a base transceiver station in a wireless network.
In a yet further embodiment of the present invention, the control processor is capable of receiving from a transceiver an inbound MAC message transmitted by the remote communications unit.
In a still further embodiment of the present invention, the control processor detects an embedded header in the received inbound MAC message and uses the embedded header to acknowledge to the remote communications unit a receipt of an embedded MAC message unit in the received inbound MAC message.
In yet another embodiment of the present invention, the control processor modifies a header in a second outbound MAC message in order to acknowledge receipt of the received inbound MAC message.
The foregoing has outlined rather broadly the features and technical advantages of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features and advantages of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they may readily use the conception and the specific embodiment disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.
Before undertaking the DETAILED DESCRIPTION, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms xe2x80x9cincludexe2x80x9d and xe2x80x9ccomprise,xe2x80x9d as well as derivatives thereof, mean inclusion without limitation; the term xe2x80x9cor,xe2x80x9d is inclusive, meaning and/or; the phrases xe2x80x9cassociated withxe2x80x9d and xe2x80x9cassociated therewith,xe2x80x9d as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term xe2x80x9ccontrollerxe2x80x9d means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.